In conventional manner, the technique of "optical integration" makes it possible to create waveguides in a dielectric substrate, generally glass, by locally increasing the refractive index of the glass. These waveguides are made by the method of diffusing ions into the substrate or by the method of depositing layers having a refractive index greater than that of the substrate.
Such integrated optical components are being used more and more in the fields of transmission by means of optical fibers. They are made small in size with their waveguides at very small spacing, and they are suitable for making up various different coupler structures. These different coupler structures include, in particular, Y-couplers having a common branch referred to as the inlet and connected to two "outlet" branches which are at a very small junction angle to each other. These structures also include, for example, proximity couplers having two waveguides which are very close together, at least in a central portion, or other types of coupler which are also known per se.
The main problem encountered in industrial use of integrated optical components is the accuracy with which optical fibers need to be aligned relative to the substrate waveguides. This accuracy is of the order of one micron or less. It is difficult to obtain because of the lack of strength of optical fibers. It is all the more difficult to obtain because the ends of the fibers are close together, leaving little or no freedom for final adjustment by micromanipulation of the fibers.
Thus, it is common practice for integrated optical waveguides to be formed on the glass substrate with their ends far enough apart to enable individual fibers facing the waveguides to be manipulated and to make it easy to bond them to the substrate.
In addition, in order to ensure good mechanical behavior of the fibers while they are being put into position facing the waveguides, and optionally being subjected to final adjustment by micro-manipulation prior to being bonded to the substrate, integrated optical components are known, in particular from the documents FR-A-2 574 950 and FR-A-2 612 302 in which the glass substrate includes not only the waveguides that are formed therein, but also grooves for positioning the fibers. These grooves and the waveguides are aligned as accurately as possible. According to those documents, the grooves are integrally molded in the substrate and the waveguides are formed subsequently on the substrate. This method of manufacture is lengthy and difficult. It requires adjustment by micro-manipulation for end-to-end jointing of fiber after fiber facing the various waveguides.
Document EP-A-0 283 301 also describes a component for end-to-end jointing of fibers to waveguides, the component being constituted by two facing groove plates in which the fibers are held. Each fiber is stripped and has one of its ends lying in the front face plane of the component. This end is fixed to the end of one of the waveguides, by the components being fixed to the substrate. In a variant, the covered fibers are held in the end-to-end jointing component each having a stripped end projecting a little from the component and being bonded to the end of a waveguide when the component is fixed to the substrate.
An object of the present invention is to make it simpler and cheaper to obtain optical devices having integrated optical components with fibers joined end-on thereto, and in particular providing considerably improved mechanical strength in traction.